Accurate and diverse genetic indexes
Dairy goat breeds indexes

Summary of the article

French genetic evaluation of dairy goat breeds indexes offer 8 main indexes on specific criteria and varied: 5 elementary yield indexes milk yield, fat and protein contents,...), 1 economical composite index et 1 global morphology index global ((udder health, udder height, rear udder, rear udder attachment, etc.).

This enables each breeder to make the best-informed choice based on the combination of traits that best fits their performance targets and priorities.

The Institut de l’Elevage is the official authorized publisher of the French genetic merit indexes for all assessed stud animals in cattle, sheep and goat breeds.

 Production indexes

The methods and principles underpinning the evaluation of genetic value in dairy goats share a lot of overlap with those employed for genetic value evaluations on dairy cattle. The core official yield indexes computed based on performance data recorded under the milk inspectorate records scheme are:

  • ’ILAIT’: quantity of milk produced (in kg)
  • ’IMP’: quantity of milk protein content (in kg), at 5% less than the milk urea nitrogen content widely used in international publications;
  • ’IMG’: quantity of milk fats (in kg)
  • ’ITP’: pure protein content (in g/kg), at 5% less than the crude protein yield widely used in international publications;
  • ’ITB’: milk fat content (in g/kg)

The protein content index sometimes comes with a C+ or C++ grade. Bucks that are graded C+ transmit a dominant allele for alpha-S1-casein to one out of two of their male or female progeny. Bucks that are graded C++ transmit a dominant allele for alpha-S1-casein to all their progeny.

In addition to the baseline set of core indexes (’LAIT’, ’MP’, ’TP’, ’MG’, ’TB’), a composite index is also proposed: the ’ICC’ (goat composite index), which is a net economic value index combining 4 of the core milk value indexes (milk protein content [’MP’], true protein content [’TP’], milk fat content [’MG’], butterfat content [’TB’]).

The ICC calculation equation weights each core index according to its economic impact: ICC = IMP + 0.4 ITP + 0.2 IMG + 0.1 ITB

 Morphology indexes

All core morphology indexes are calculated based on a scoring system, where animals are graded by giving a score on a linear 1-to-9 scale.
The 4 type traits graded for this evaluation are: udder profile, udder height, shape of the rear udder, and quality of the rear udder attachment, which together sum up 80% of udder morphology.

They are combined into a composite index called ’IMC’ (goat morphology index) that offers sold guarantees of optimal genetic improvement across the full set of morphological udder and teat conformation traits.

There are significant physical and genetic differences between the Alpine and Saanen breeds, which is why the weightings given to each of the core morphological indexes rolled into the composite IMC vary between species.

Consequently, as with the core dairy indexes and the ICC, the IMC values are not comparable between different breeds. The IMC is expressed in relation to a baseline figure of 100, where 100 is the mean IMC value across the entire French goat population. Around ⅔ of all animals are in the range 90 to 110.


Key figures

  • 5 elementary yield indexes
  • 1 composite economic index
  • 1 global morphology index (IMC)